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Nanoscale Operando Characterization of Electrolyte-Gated Organic Field-Effect Transistors Reveals Charge Transport Bottlenecks.

Shubham TanwarRuben Millan-SolsonaSara Ruiz-MolinaMarta Mas-TorrentAdrica KyndiahGabriel Gomila
Published in: Advanced materials (Deerfield Beach, Fla.) (2023)
Charge transport in electrolyte-gated organic field-effect transistors (EGOFETs) is governed by the microstructural property of the semiconducting thin film that is in direct contact with the electrolyte. Therefore, a comprehensive nanoscale operando characterization of the active channel is crucial to pinpoint various charge transport bottlenecks for rational and targeted optimization of the devices. In this work, we systematically probe the local electrical properties of EGOFETs by in-liquid Scanning Dielectric Microscopy (in-liquid SDM) and provide a direct picture of their functional mechanism at the nanoscale across all operational regimes, starting from sub-threshold, linear to saturation, until the onset of pinch-off. To this end, we introduce a robust interpretation framework of in-liquid SDM that enables quantitative local electric potential mapping directly from raw experimental data without requiring calibration or numerical simulations. Based on this development, we perform a straightforward nanoscale assessment of various charge transport bottlenecks, like contact access resistances, inter- and intra-domain charge transport, microstructural inhomogeneities and conduction anisotropy, which were inaccessible earlier. Present results contribute to the fundamental understanding of charge transport in electrolyte-gated transistors and promote the development of direct structure-property-function relationships to guide future design rules. This article is protected by copyright. All rights reserved.
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